Sub-Doppler Laser Cooling of 23Na in Gray Molasses on the D2 Line☆☆Supported by the National Key Research and Development Program of China under Grant No 2016YFA0301602, the National Natural Science Foundation of China under Grant Nos 11474188 and 11704234, the National Key Research and Development Program of China under Grant No 2018YFA0307601, the Fund for Shanxi ‘1331 Project’ Key Subjects

Abstract

We report on the efficient gray molasses cooling of sodium atoms using the D2 optical transition at 589.1 nm. Thanks to the hyperfine split about between and in the excited state , this atomic transition is effective for the gray molasses cooling mechanism. Using this cooling technique, the atomic sample in F = 2 ground manifold is cooled from to in 3.5 ms. We observe that the loading efficiency into magnetic trap is increased due to the lower temperature and high phase space density of atomic cloud after gray molasses. This technique offers a promising route for the fast cooling of the sodium atoms in the F = 2 state.